It is because you have played so few games. The higher scores will not count and thus you get what seems to be a much lower cap that you would have imagined.

Once you have played 20 games your cap will be roughly where it should be (as it only counts the best 10 of the 20 rounds carded, taking into account the course rating, it is known as a differential).

EDIT: just checked and they really shouldn't have given you a cap until you entered more than 5 scores. Here is the table of how many differentials are used in relation to total rounds entered:

Rounds Entered Differentials Used
5-6----------------1 lowest
7-8----------------2 lowest
9-10---------------3 lowest
11-12--------------4 lowest
13-14--------------5 lowest
15-16--------------6 lowest
17-----------------7 lowest
18-----------------8 lowest
19-----------------9 lowest
20----------------10 lowest

__________________
Personal bests:
18 holes - 92 (+21 02/08/06), 92 (+20 24/06/07)
9 holes - 43 (+7 02/08/06), 41 (+7 24/06/07)
Putts (18) - 30 (04/09/07)
Putts (9) - 12 (02/08/06)
Fairways - 11/14 ((02/08/06, 24/06/07, 01/08/08), 10/13 (09/06/07)
GIR - 5/18 (01/08/08)
Pars in one round - 7 (24/06/07)

Lifetime birdie count - 8 Latest - 03/09/08 - 7th hole Kingsway 318 yard par 4
Lifetime eagle count - 1 Latest - 15/06/08 - 4th hole Canadian G&CC 9 hole 481 yard par 5