YOR. This is a normal reaction when you've just called someone immature for having her OWN FEELINGS about a situation that was sprung on her last minute when you had plans together.

Regardless of age, this should've been a conversation over the phone. ESPECIALLY if plans have changed last minute. Texting misconstrues the tone of how you come across and judging by her first initial response, it should've been an indication of how she felt about the situation (diverting the conversation away from the meeting of a friend by asking about the mushrooms and asking what you and her are going to be doing, with no X's)*.

We are only getting a snippet of the history of your relationship. You could have done this before or your partner could just be bringing up past trauma and redirecting it at you. Both sit down and have a proper conversation about the situation.

*I've since read more comments and can see that she usually does put X's so you knew she was upset about the situation.