Although figures I have show a slightly greater LDR of 1,660m for the CRJ900, even your 1,596m gives a WET LDR of 1,840m. That is well above comparable types and the A320/321/B717 for example so it's perhaps not surprising that SEN's 1,604m LDA can cause a problem.
I should be interested to know how often the SEN ATIS states the runway as being WET.