Compiler Bug? Nearly identical code compiles differently

I'm sure you are all (including me) skeptical that what I have is a compiler bug. But I can find no other explanation. I have two lines of nearly identical code assigning a value to an array. But the compiler creates very different output for the second line. In fact, it doesn't assign the value to the array at all.

Here's some excerpts of source code with the troubling line highlighted in red:

...
static U16 mu16aPulseTripPointPerSet[2];
static U16 mu16aTimerPeriodPerSet[2];
...
// Initialize the timer period
mu16aTimerPeriodPerSet[0] = 0xffff - FSK_F1_COUNT;
mu16aTimerPeriodPerSet[1] = 0xffff - FSK_F2_COUNT;

// Initialize the trip points
mu16aPulseTripPointPerSet[0] = mu16aTimerPeriodPerSet[0] + 2 * FSK_F1_COUNT / 3 + FSK_TRIP_POINT_OFFSET;
mu16aPulseTripPointPerSet[1] = mu16aTimerPeriodPerSet[1] + 2 * FSK_F2_COUNT / 3 + FSK_TRIP_POINT_OFFSET;

FSK_BurstStart();

And here is the corresponding listing output with the trouble code highlighted:

                                           ; SOURCE LINE # 258
0011 7500FE      R     MOV     mu16aTimerPeriodPerSet,#0FEH
0014 7500C5      R     MOV     mu16aTimerPeriodPerSet+01H,#0C5H
                                           ; SOURCE LINE # 259
0017 7500FF      R     MOV     mu16aTimerPeriodPerSet+02H,#0FFH
001A 750018      R     MOV     mu16aTimerPeriodPerSet+03H,#018H
                                           ; SOURCE LINE # 262
001D E500        R     MOV     A,mu16aTimerPeriodPerSet+01H
001F 24D8              ADD     A,#0D8H
0021 F500        R     MOV     mu16aPulseTripPointPerSet+01H,A
0023 E4                CLR     A
0024 3500        R     ADDC    A,mu16aTimerPeriodPerSet
0026 F500        R     MOV     mu16aPulseTripPointPerSet,A
                                           ; SOURCE LINE # 263
0028 E500        R     MOV     A,mu16aTimerPeriodPerSet+03H
002A 24A1              ADD     A,#0A1H
                                           ; SOURCE LINE # 266
002C 120000      R     LCALL   L?0039

You see that see that the second assignment simply assigns some values to the accumulator and that's it! If add a 3rd line of nearly identical code, they all create the correct output. If I change the order of the statements, it also produces the correct output. Turning off optimization had no affect. I tried a bit to create a reduced program which demonstrated the error and I was not able.

I can work around this problem for now by simply changing the order of my statements. But it is alarming to me. Any ideas what could be causing this?

Thanks.