MacBook Pro display issue - can anyone help?

My MacBook Pro, dating back to 2012, has started acting odd on startup, or waking from sleep.

The display goes an odd white-ish colour and is covered in coloured vertical lines. Now, I know that many people have experienced this before - but the odd thing is the problem ceases around 10 seconds later and returns to normal. I'm then able to use the laptop as usual.

My concern is that this is a sign of a more serious problem that I could perhaps solve now, if anyone has any idea what's going on? Obviously, I've got my fingers-crossed for a simple fix!

Any help would be much appreciated. Thanks.