Accidentally called my ex?

Hi, my ex and I who went out for 4 years broke up 4 months ago, and I haven't called him since. I did try to get back with him but i didn't. I have been trying to move on, but forgot to delete his number from my phone. Yesterday, I accidentally called him when I sat on my phone and it lasted 1min44secs. I think it went straight to voicemail and he most likely didn't even pick up. I noticed that his number was dialed when I checked my phone this morning. I have such bad luck. I had wanted to send him a xmas greeting (gift/card) too but now after this accidental phone call, he might think that my xmas greeting is a tactic to try to get him back even though I plan to write "i wish you luck in your future endeavors." What should I do? Should I text him "sorry i noticed i accidentally called you yesterday, not sure how it happened?" If i don't tell him that it was an accident, he may think I wanted to reach or bother him. Any better suggestions? Thank you.