Hm, should I or shouldnt I?

Absolutely find an agent. Publishers contracts are written to protect publishers. If you haven't negotiated contracts with a dozen publishers over the years, then you have no idea what to look for and try to change in a contract. An agent does.

Briefly.

My two-cents

I suspect you will not have a hard time landing an agent if you already have a publisher who is interested.
The most important thing now is to find the "right" agent for you and your future as an author.

All good wishes to you!

Yes, but who wants an agent that is just interested in grabbing the deal. The agent you REALLY want is the one who wants to rep you when there's no deal on the horizon. That's the agent who loves the book.

Doesn't the friend who submitted the manuscript have a lead on a good agent for you? Her own, perhaps?

I found myself in this position: having publisher offer contract before I found an agent who loved my story. My choices were few: sign without an agent, or send another round of queries out and mention the contract. I did have one agent who turned down the deal because she wasn't right for my story (and I respect the heck out of her for that), but 8 out of 10 responded positively (one was out of town and I got an auto-reply!). What's a poor, unagented first timer to do but pick the agent at the top of her list? It's like being between a cloud and a fluffy place.