i introduced a new guinea pig to one of mine that i already had and that was about 2 months ago, and for the last month and a half my one that i have had previously has been purring at the new one like going up to her slowly and purring at her butt. i thought she was in heat at first but i think that’s too long of a time? what does this mean? also they get along and they don’t ever fight unless she gets mad at the other one for going up to her butt.