The Doctor had made a simple mistake by taking the Gelfling's hand. The myths and legends had mentioned their abilities, of course. But when a species is gone, there's no way to test which parts of myths and legends are true.

The fact that they were touch telepaths was true. But the Doctor had no idea of the kind of telepath they were. "Touch telepath" simply defines how the ability is used. It doesn't really talk about what kind of ability it is.

So, when she took his hand, he sensed immediately that she was a telepath. And a powerful one at that. Not as powerful as some Time Lords and certainly not as powerful as the TARDIS - but powerful enough that he wouldn't hurt her. There was a small comfort in that.

A part of the Doctor wanted to put up all of his defences. But the part of him that was curious, won out. He still held her hand, but slowly sat back down. It would be bad if something happened and he fell on top of her. He closed his eyes, more to focus than anything.

He spoke softly into her mind. His voice here, had a gentleness and serenity that his current physical form could never quite manifest. "I am a telepath too. Do you know what's happening?"

He assumed she did, but it's always best to check.