If she's soaking in her water bowl, that doesn't sound like a very gravid snake, that sounds like a snake prepping to ovulate. When did she ovulate for him? The only way for her to be gravid is if she ovulated, and if she only locked up with the male spider in March, then she's extremely unlikely to be gravid. It sounds like she is preparing to ovulate, which would initiate the process of being gravid - once she ovulates, then she'll begin coiling on the heat, go into the prelay shed, and so on and so forth.

-Jen