It is too big. Your sig is 244 pixels tall on its own and the spoiler adds another 40 pixels, making it 280 pixels tall when it should be 250.
Edit: When in doubt, measure it.
Second edit: Mods can't see everyone's sig and even when they do they don't usually sit there and measure every pixel xD I wouldn't imagine. I think most of the time it's other users using the report button, helping the mods catch it. My very first sig was a few pixels over the limit and it stayed that way for about 2 weeks before someone probably reported it. I stayed just on the mark this time around (measured it and everything) just to make sure I don't get another infraction.
Edit 3: Sorry just read Prin's response and everything in the spoilers does not count, that's what spoilers are for to put more stuff in your sig without making it huge. The spoilers count as 40 pixels only from what I've read from mods(correct me if I'm wrong).