Andy
Yes, it is normal. The act of taking the cutting has delayed the genetically determined growth period, so it will try to grow as late into the winter as it can to complete its growth cycle. However, you should make sure it still gets a chill period. Keep it between about 28F and 40F as much as possible. It is critical for it not to fall below the low temperature as new Acer roots are very susceptible to freeze damage.
Brent
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