@Notso,
That is pretty weird alright.
I did want to point out that in your OP you said;
"I thought I must have accidentally hit a button that limited the Gs but there is no such thing that I'm aware of."
There is a switch that does limit the amount of G's you can pull when you have a load of ordinance. It's the CAT I and CAT III setting. Generally, CAT I is with a A/A load-out (missiles and centerline tank IIRC) so a light A/C. And, CAT III is anything over that, typically an A/G mission.
However, CAT III would not limit you to that degree. I think it's a 4.5G limit. You will get a caution light if it's set incorrectly. Although that may still be WIP.