The visitors were expected to run out more comfortable victors against a side that have not won a match for almost a decade, but Coleman revealed that he never felt it would be easy, particularly on Andorra's controversial 3G pitch.
"We have a lot of fans here in our hotel and before the game they were saying that they wanted at least three goals - but we knew it would not be easy," he told Sky Sports News.
"Andorra's record here is not good but they are a fighting nation and I have seen the Netherlands struggle here. I can say it now but when we arrived and saw the state of the pitch my heart sank. It shouldn't be allowed at this level, but we got the three points and everyone else has got to come here and play. It's a great start for us.
"There were half a dozen challenges that weren't very good. The referee should have clamped down but he let it go and we are a bit disappointed with that - we had a bit to contend with tonight."
Andorra's sixth-minute penalty was their first goal in a competitive match for four years and also saw them take the lead in a European Championship qualifier for the first time ever.