Attorney Took My Case, Discussed It With Me, Got All Of My Info And Evidence, Then Later Notified Me He Had A Conflict. Is That Legal? (oklahoma Usa)

I've had an ongoing issue with a newly built house for over a year. The builder has been stringing me along but never resolving it so I consulted with a local attorney.

We had an initial meeting with the attorney where we went over everything in detail. I should note that at the beginning of this meeting he asked who the builder was and I told him. He also asked what documentation and evidence we had, and went over in detail what our expectations were and what we considered to be our "optimal solution" and our "minimum we'd settle for if we had to" solution. He said the plan would be to write a demand letter with a time limit to fix the issue, and then file a lawsuit if it's not addressed.

He ended the meeting by asking me to email him all of the documentation, photos, and communication with the builder. He said he'd get to work on it as soon as I emailed him the info. A few hours after the meeting I emailed the attorney the information he'd asked for.

Two days later the attorney contacted me to say that he has a conflict because they are (or have in the past?) represented this builder. He can't take our case and told us to find another attorney. He won't charge us anything for the initial meeting.

Shouldn't the attorney have checked for conflicts before the initial meeting and getting all of this information from me? He now knows everything about our side of the case, along with the minimum we'd be willing to take for a settlement. And he may end up representing the builder!

Is it normal for an attorney to only check for conflicts AFTER the initial consultation? My gut says that he make an honest mistake, but I guess there's no way to know for sure. Is there anything illegal or against the rules about how he handled it? Is there anything I should do?