Well Pets Mart large crickets are typically about 4 weeks. Yea that is too big for her. You want to feed her a size that approx. fits between her eyes. I am sure she will be fine just make sure she is basking and that she poops in the next couple of days. It was one so it should be not a big deal.
The reason you have to be careful with beardies is they can easily become impacted and not able to go poddy. I doubt one cricket will do that. Once she poops after eating that cricket all should be well. Don't forget to offer her greens everyday!! She may not eat them but keep offering. Its a good practice to get her started on right away.
This is a great site for food....kind of like the beardie food bible.. http://www.beautifuldragons.503xtrem...nframeset.html
by the way congrats on joining the beardie club....you are going to LOVE IT!!!!!!!