Hi Rick,
When a significant score drop occurs on Test Day (such as the one that you described), it's usually due to one (or both) of the following:
A) Something about your studies was "unrealistic" relative to the Official GMAT
B) Something was "off" or "surprising" about Test Day and this difference muddled your performance.
Since you're focused on your prior CAT results, here are some thing to consider:
1) Did you take the ENTIRE CAT (including the Essay and IR sections)?
2) Did you take either of these CATs more than once?
3) Did you see any of the questions on these CATs before (such as in this Forum)?
4) Was there ANYTHING about how you took these CATs that did not match up with how the GMAT is administered?
5) What time of day did you take your CATs and what time of day was your GMAT?
There are also other things to consider:
6) How did you sleep the night before your GMAT?
7) How long is the ride to the Test Center from your home?
8) What did you do the week before your GMAT?
9) Were there any surprises or distractions at the Testing Center?
The fact that you had 5 minutes for the last 2 Quant questions means that you were moving fast through that section. That's usually a BAD sign - it implies that you're likely moving too quickly and making silly mistakes as a result.
Since you technically achieved your score goal, are you planning to retest?
GMAT assassins aren't born, they're made,
Rich