This is a well known Lyft issue, which is currently not under our control. It occurs in the situation when there is up to 25 min left till the pickup time, but the driver who was assigned to that pickup (not you) has refused to go ONLINE with Lyft to make the pickup.
In such case, Lyft puts the pickup back to the market, and Skeddy books it for you.
As a result, you get a push notification about a newly booked ride, but you probably have less than 10 min to get ONLINE with Lyft and accept it.
Note: That happens because this pickup has just become available, but not because the proper push notification was not sent to you in the past.
To cure the glitch, we're currently in process of adding a time filter to Skeddy, so you will be able to specify the time frame (e.g. 1 hour or 30 min) in which you want to receive the scheduled pickups.