window increasing

[krisver]

Hi,
I'm using speakeasy in one of my project and I have problem with window under the verification function.
Code looks like that:

var tokenValidates = speakeasy.totp.verify({
secret: secret.base32,
encoding: 'base32',
token: '123456'
});
everything was working, but month later I couldn't login because verification failed. I added window: 2 and everything start to work. Another month later the same issue, when I increased window to 4 again everything start to work, why is it working like that I cannot all the time increasing this value. What to do with this?
Thank you for a quick replay.