Trouble pushing to u-boot-tegra

Tom,

I haven't had to push an update to master on u-boot-tegra in several months, but I've got a new PR that needs to go in. I've tried my normal 'git push ssh://gu-tegra@git.denx.de/u-boot-tegra master', but it's not working.

I get:

gu-tegra@git.denx.de: Permission denied (publickey). fatal: Could not read from remote repository.

Please make sure you have the correct access rights and the repository exists.

Has something changed in the last (several) months? I've also just upgraded from 16.04 Ubuntu to 18.04, but everything else is working OK, so I'm not sure it's all my fault, but it may well be. :)

Thanks,

Tom