Contractor that raise agreed price after taking deposit.

[Charles Situ]

I have a roofer that realized that he underestimated the scope of a roof replacement after he accepted my deposit and now he is asking for more money. Even with the additional money he is asking for, his price is still lower than other bids. His original quote was $8.7K versus another roofer at $10.9K and $15K from the roofer my PM uses. I spoke to 3 of the roofer's prior customers, whom were happy with the work. The roofer also don't have much online reviews and said they need my referral and therefore is very incentivized to do a good job. After submitting 50% deposit so the roofer could purchase the materials, he found heavier slate shingles beneath the architectural shingles. He said that the dumpster company will charge him more for the heavier weight and the tarp he will be using to protect the side of the house will be torn from the slate, and therefore he needs an additional $1.5K. I felt bad for the guy because according to what my PM got from other roofers, it is likely that he isn't making much money at the $8.7K. I agreed to the additional money, but only after the job is completed. Was that the right move?