Certainly, every polling company is now showing a further move towards the SNP since early April. I am still, to put it mildly, shocked at the level of support the polls are showing for the SNP and the fact that Labour are registering sub 30.
I doubt these sorts of numbers will happen on election day.
One opinion poll stuck in my mind while I was watching Liverpool FC's treble winning tour of the city in 2001. It had Labour on 54% and the Conservatives on 26%.
That parade took place on May 20th and the general election happened on June 7th - a gap of 18 days.
In the end Labour finished 13% less and the Tories 6% more than that poll. Doesn't prove anything obviously but it taught me to be very sceptical of very large leads for a particular party over another.