I've worked a lot of contract jobs and very few straight jobs. I would love to have a really good straight job at this point in my career, but the contract work wasn't bad at all. It's usually worse benefits. And make sure it's W-2 and not 1099, or you'd better ask for a lot more money, because you'll pay double the taxes you're used to. I learned a lot because it's usually a very diverse environment in terms of people's experiences, so there are lots of different perspectives from the jaded pro to the recent grad.

I've been doing this for 25 years and I'm slowing down and getting tired of constantly being in team building mode. I want a straight job where I can build up specific expertise and relationships and use my experience on a single set of products/services. But I don't regret my contracts. I mean I could tell horror stories about a couple of really shitty contractors I worked for, but the actual job and people I worked with were great even so.

As someone else said, if you back yourself to get something else later then it could be the right move.

Only thing I'd be concerned about is the idea that they snuck the contract thing in - it would depend exactly what you mean by that, but if they were trying to conceal it from you then that might be a bad sign. If it was just a miscommunication or whatever, then hopefully all good.

Good luck, whatever you do!

PS - forgot to say that I quit a permanent job to go freelance and it's been a big improvement in my life. I work from home, make a bit more money, and can be much more flexible. Downside is less income security, and as a result less favourable terms on things like mortgages. Also, I have been lucky that I basically get regular work from a small agency and have done for a number of years, so I rarely need to go hustling for clients.

Ask yourself, in 6 months time will you be able to find another contract job or employed job easily? If the answer is yes then I'd say go for it and get the extra experience.