Gsellman hasn't pitched the last two days due to triceps soreness, Deesha Thosar of the New York Daily News reports.
The Mets don't appear to be considering a trip to the injured list for Gsellman just yet, but if his absence lasts much longer, he may need to hit the IL. His last outing dates back to Sunday, when he surrendered two runs on two hits over one-third of an inning.