Date.php error but everything functioning well

I am getting the following errors showing in the piwik dashboard
Piwik appears to be operating correctly. I have the servermonitor munin plugin installed.
Running on Debian 7 with Apache 2.4

WARNING: /var/www/piwik/core/Date.php(262): Notice - A non well formed numeric value encountered - Piwik 2.15.0

Hi @zeigerpuppy

Could you create a bug report on Issues · matomo-org/piwik · GitHub with the URL you use to reproduce this issue?

Oddly, the error has stopped happening, I’ll post to github if it recurs!