yes it is. hilbert has no claims to originating the theory of general relativity, and he had been talking with einstein before this, even inviting him to give talks. einstein already had the ideas of general relativity much earlier than when he, and hilbert, finally published his final theory. hilbert simply had a better command of the mathematics and was able to put things together once einstein had already come up with the physical theory and much of the mathematics.
in fact, einstein was originally a little annoyed with hilbert in that he felt hilbert tried to come in at the end and shore up the final mathematics before einstein could. it isn't as though hilbert was working independently during this time, independently discovering general relativity.