Not really. It's not surprised that there are always something new needed to learn in a new company while the important point is the employer knows how long it takes a person to get that level. Based on my experience, lots of managers know nothing about the details of a position and they maybe overestimate or are too optimistic about the position. In this case the new hiring will become the soapgoat when a failure occurs.
the best approach is to let them know your skill set and your backgroup and communicate with them in order to get the same understanding about the position and the advancement of the position.
Of course you should know how long it takes you to get the skills and how much risk you need to take.