Don't worry about it. Your memory is not at fault 'with' was usual when I was at school. Ours is a living language and every generation changes it a little. The only languages that don't change are those that can't be changed because they are dead and have no native speakers. Your parents and grandparents no doubt complained and perhaps still do about your usage and mine certainly did about mine.
This has probably appeared because of people mishearing unstressed 'with'. I am certain I've been hearing it for at least 30 years. At present it is not totally acceptable but given another generation it will be. We can't stop such changes and it would be wrong to try. Can you imagine how strange it would be if we all suddenly started speaking like Shakespeare? Well, if similar changes hadn't occurred over the intervening years we would be speaking like him today. This change is just one of many and not at all important.