Good idea, now that I got the thing clean (all day yesterday) and waxed (1/2 day today) I'll be going under with the crawler in a day or two...No problem at all.
My opinion, based on your description is that you were hitting front bump stops, possibly even bottoming them out. I haven't personally bottomed mine out (yet), so I can't really say what that "feels" like, but I think if you did actually hit the frame that would be fairly noticeable as the whole truck would kind of shudder.
Take a look underneath and see if there is any scraping marks on the frame or anything underneath. my bet is there isn't.
Here is another similar thread on the subject that may help: (1) Mojave bottoming out | Jeep Gladiator Forum - JeepGladiatorForum.com