Difference in maximum level of I and Q channel in Rectangular QAM modulation

Hi,

I am working on simulink model of 16 qam modulation.I am using the rectangular qam modulator block in simulink.I noticed that maximum levels of I and Q channels after pulse shaping is different.But the I and Q maximum levels were same as expected before pulse shaping filter.It was the same even after up sample stage and was passed through same pulse shaping filter. Please tell me some possible reasons for such a difference in maximum levels.

Krishnakumar