But he was back for Sunday's clash with Wales and made his presence felt, putting in a big tackle on Alun Wyn Jones in the first half, in a game which ended 16-16.
And Trimble, who has one GUINNESS PRO12 try this season in nine appearances, was simply happy to be back on the international stage.
"I was pleased," Trimble told the Belfast Telegraph. "I was just very excited to be back in a green jersey.
"I just wanted to make my mark as much as possible. There was a lot of hard work out there but a draw was probably a fair result.
"I didn't get too many carries but I was busy defensively and we had to cover a lot of metres.
"The physicality was through the roof; it was just very, very demanding. There was a lot of work for the back three."
Against Wales Trimble was being led by Ulster teammate Rory Best on the international stage for the first time, and the wing is convinced the hooker showed he is up to the challenge.
"Rory has led me personally for a long time, he's led Ulster for a long time," Trimble added. "We're very proud of him.
"Ulster as a province are so proud to have Rory in there as captain of Ireland. It means a lot to us that he's there and I thought he performed well."
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Guinness PRO12 Ulster News
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